#include "public.h"
#include "key.h"
int which_key_press()
{
	while(1)
	{
	delay_10us(100);
	if(K1==0||K2==0||K3==0||K4==0)
	{
		delay_10us(100);
		if(K1==0) return 1;
		if(K2==0) return 2;
		if(K3==0) return 3;
		if(K4==0) return 4;
	}
	}	
}